According to the American Medical Association (AMA) Citation Style, you need as many of the following components as you can identify to cite a website:
Author (can be an organization)
Title of the specific item (section of the website, etc.)
Name of the website
URL
Published date (if available)
Updated date (if available)
Accessed date
Example (author)
Rainie L. The rise of the e-patient. Pew Research Center Internet and the American Life Project website.